Majority Element

Problem statement

Given an array nums of size n, return the majority element.

The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array.

Example 1: Input: nums = [3,2,3] Output: 3

Example 2: Input: nums = [2,2,1,1,1,2,2] Output: 2

Solution

class Solution:
    def majorityElement(self, nums: List[int]) -> int:
        candidate = None
        count = 0
 
        for num in nums:
            if count == 0:
                candidate = num
            count += 1 if num == candidate else -1
 
        return candidate

Explanation

boyer-moore-majority-vote is the way to solve this issue. You can have a look at the other article.

TLDR; The Boyer-Moore voting algorithm finds the majority element in an array by using a simple voting system where different elements cancel each other out (by decrementing a counter) while matches increment the counter. When the counter reaches zero, a new candidate is chosen, and since the majority element appears more than n/2 times, it will always survive this elimination process and be the final candidate.